Fixture key



Dec. 14, 1954 J. 5. APPLETON 2,696,765

FIXTURE KEY Filed March 5, 1952 T L 4 INVENTOR: 7 BY J SflPPLUO/V flTTORNE X United States Patent 6 2i 2i765s Joe S. Appleton, Gardena,Calif:

Applicatibh-MarcbS; L952, Serial No 274,947

3" Claims. (6]. 90-59)" Th s; nvention. relatesto. keys. or. sc e jig-s.and fix ures 11 the tablesof. ools.

Various types of locating devices, generally termed fixture keys, arenow in use and will serve satisfactorily in cases where the seats forthe keys in the bases of the jigs and fixtures and the grooves or slotsof the machine tables are made and held to correct shapes and sizes.However, it is found that the wear due to recurrent seating of keys tomount such jigs and fixtures on machine tables tends to change the shapeand size of the key and of the openings in which the keys are seatable.While the effect of such wear ordinarily might be considered negligible,it will be appreciated that, in precision manufacture, where the sizesof such fixture keys are held within limits of .0005 of an inch and theopenings for receiving the keys are similarly held within close limits,even the effect of slight wear will be found of importance.

It is in view of the foregoing the object of the present invention toprovide a fixture key which is designed and constructed to maintain itssize and shape over a long period of time. A further object of theinvention 1s to provide means within the key of my invention foradjusting the size and shape of the key to make up for such slightvariations as may develop due to wear of the contacting surfaces to theend that the same close tolerances may be maintained over a long periodof repeated use of the keys on the same machine. Another object is toprovide means for seating the key in the base of the jig or fixture incorrect parallel alinement with the grooves of the machines tables.

These and other objects of the invention together with the advantageousfeatures thereof will be appreciated upon perusal of the followingdetailed description and by referring to the accompanying drawings inwhich a preferred form of the invention is illustrated.

In the drawing:

Fig. 1 is a side elevational view of a fixture key embodying theinvention;

Fig. 2 is a substantially corresponding end view of the device;

Fig. 3 illustrates the method of alining keys for insertion into thebase plate of a jig or fixture; and

Fig. 4 shows the key applied to locate such fixture base plate on thetable or bed of a machine.

The key of the invention includes a relatively large base 1 havingparallel side surfaces 2, 3. The width of this base is calculated toseat the key snugly in a groove A of the machine table, substantially asindicated in Fig. 4 of the drawing. A cylindrical shank 4 rises fromthis base to engage a hole, or socket B of the tool C to be machined.The inner end of this shank is at 6 shown slightly recessed to insureclearance when the key is mounted in position for complete seating ofthe key.

As above explained, the diameter of the key shank 4 and width of thebase 1 are held to very close tolerances in order that the key may besnugly seated to insure correct positioning of the tool on the machinetable. But even when tightly fitted, it is found that repeated seatingof the keys will result in wear on the contacting surfaces suflicient toaffect the correctness of the position of the tool on the machine table.It has, for this reason, been suggested slightly to taper the sides ofthe key base and the cylindrical surface of the shank to facilitateseating of the key and to insure tight fit when fully seated. Butbecause in this case only a small portion of each of the engagingsurfaces of the key becomes tightly seated, it is found that theseportions of the surfaces become worn "ice 9. mush ta tes hansush: tanninec mesdetrimental rather th l s ve.ets ih i ii sd;screw. .h as Blue,and; when. th shank s. a ial y :{HP n. qats a t. t auna; hat the. ke max1 ea 1 he tea bas Should" ensbe t 741 1. e, ldj i h l innasit on hs ein,

t; m asl tenu ed; t9. entrance the. pipe. p u int the recess of the" keyuntil the p'rop,er fit? is obtained, When. t. sitne o. emsr lth t ke minasket. t Pip l .ia ra tsln we in. kex sy thsst ts e di yjw. hslt.nldingsw ar qni l ei pm sy seat has occurred. While in the drawing onlyfour slots 9 are provided, it is to be understood that the number ofslots may be varied where it is found more advantageous to do so.

The base of the key should be similarly adjustable and this may beaccomplished by boring a slightly tapered hole 10 through the middle ofthe base parallel with the side surfaces thereof. A narrow slot 11 issunk into the base through the axis of this hole, substantially asindicated in the drawing. A tapered pin 12 is fitted into the hole ofthe base and this pin may be advanced therein after the key has beenseated in the slot A of the machine table, as indicated in Fig. 4, totake up any slight clearance that may be found between the abuttingsurfaces. More delicate adjustment of the base may be obtained bythreading one end of the pin, as indicated at 13 to engage screw threadsof the base perforation and 3y slotting the other end of the pin toreceive a screw r1ver.

When the base is equipped with such spreading means, it is seen that thekey may be placed in and removed from the machine bed slot an indefinitenumber of times without danger of any wear occurring.

One difficulty generally found in mounting fixture keys in the base of ajig or fixture for seating in a slot of a machine table is the aliningof the key bases with the slots of the machine. If the keys are soloosely seated in the tool base that they may be manually seated in thesocket of the fixture base and rotated therein to aline with the slots,there is nothing to retain them in position while being held in storageand carried to and from the machine. lt is, for this reason, foundimportant to devise some means for alining the key bases when they areseated in the tool base and retaining the keys in alined position untilmounted on the machine table, Such means may take the form of a guidemember 15 having a straight groove 16 sunk into the surface thereof of awidth to receive therein the key bases for correct alining after the keyshanks have been inserted in the socket of the fixture. If the key basesdo not fit tightly within the groove, it is merely required to apply ascrewdriver to the slot of the element 12 and lightly to rotate theelement to obtain a snug fit insuring correct alinement. The pipe plugs8 are thereupon similarly adjusted, if found necessary, to fit theshanks of the keys snugly within the tool sockets. The guide member 15is then withdrawn and the tool may be seated in the slot of the machinetable. When the guide member 15 is hardened and ground to the exactsize, it is found that the key bases will seat tightly in the groove ofthe machine table. But should this groove be found so badly worn thatthe keys do not fit tightly therein, it is merely required to turn theelements 12 to spread the bases of the keys until firm contact isobtained. It is seen from this description that the member 15 forms agage for correctly seating of the keys which may be used in this mannerindefinitely without showing signs of wear. Also that the key shanks andkey bases may be adjusted and readjusted for correct seating over anextensive period of time Without showing signs of wear. But while I haveillustrated a preferred form of the invention, it is to be understoodthat modifications of arrangements, proportions and shapes, within thescope of the claims hereto appended, may be embodied therein withoutde-. parting from the spirit of the invention.

I claim:'

1. A key for locating a fixture on a machine bed, said key including abase having parallel side surfaces seatable in a groove of the machinebed and a cylindrical shank seatable in a socket of the fixture, meansfor spreading said base to move the parallel side surfaces thereofagainst the sides of said groove, and means for expanding said shanksnugly to fit the shank within said socket.

2. A key for locating a fixture on a machine bed, said key including abase having parallel side surfaces seatable in a groove of the machinebed and a cylindrical shank rising perpendicularly from the base, theshank being axially recessed and slotted, means seatable in the recessof the shank to expand the shank tightly to engage the socket of thefixture, the base being lengthwise slotted, and means seatable in theslot thereof to expand the base to move the parallel surfaces thereofagainst the sides of the machine bed groove.

3. A key for locating a fixture on a machine bed, said key including abase having parallel side surfaces seatable in a groove of the machinebed and a cylindrical shank rising perpendicularly from the base, theshank having a tapered and threaded recess axially sunk therein andprovided with axially directed slots, a tapered screw seatable in thethreads of the recess to expand the shank tightly to fit within thesocket of the fixture, the base having a tapered hole through the middlethereof parallel with its side surfaces and a narrow slot sunk into thebottom surface thereof through the axis of the hole, and a taperedelement seatable in the hole to expand the base to move the parallelsides thereof against the sides of the machine bed groove.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 674,074 Bennett May 14, 1901 744,559 Kendrick Nov. 17, 19032,372,716 Evans Apr. 3, 1945 2,479,075 Martin Aug. 16, 1949

